Memory-based pufs

<p>A <a class="wikilink" href="/physical_unclonable_function/">Physical Unclonable Function</a> relies on a manufacturing process with a level of stochasticity that makes it impossible to reproduce. In <a class="wikilink" href="/semiconductor_industry/">semiconductor industry</a>, this happens with RAM memory: at the moment of power up, each bit will get randomly assigned values of $1$ or $0$. This is unique to the chip, and can't be controlled (similarly to what happens with <a class="wikilink" href="/arbiter_pufs/">Arbiter PUFs</a> using the MUX design). </p> <p>There are some subtleties in the architecture in order to define what is a "Challenge", given that the bits are already set since power on. </p> <p>As far as I understand, these types of PUFs show a high degree of correlation (when there's a $1$ there's a higher chance of having another $1$ close by) limiting the total space. They can also be inspected from the outside in a non-destructive test, allowing some form of impersonation (given the bit is set at power up, it is already available). </p> <p>On the other hand, as far as I understand, they are easy to manufacture, quite stable over time, and with good error correcting algorithms in case there is drift over time.</p>